A solution for measuring accurate reaction time to visual stimuli realized with a programmable microcontroller.

This article presents a new solution for measuring accurate reaction time (SMART) to visual stimuli. The SMART is a USB device realized with a Cypress Programmable System-on-Chip (PSoC) mixed-signal array programmable microcontroller. A brief overview of the hardware and firmware of the PSoC is provided, together with the results of three experiments. In Experiment 1, we investigated the timing accuracy of the SMART in measuring reaction time (RT) under different conditions of operating systems (OSs; Windows XP or Vista) and monitor displays (a CRT or an LCD). The results indicated that the timing error in measuring RT by the SMART was less than 2 msec, on average, under all combinations of OS and display and that the SMART was tolerant to jitter and noise. In Experiment 2, we tested the SMART with 8 participants. The results indicated that there was no significant difference among RTs obtained with the SMART under the different conditions of OS and display. In Experiment 3, we used Microsoft (MS) PowerPoint to present visual stimuli on the display. We found no significant difference in RTs obtained using MS DirectX technology versus using the PowerPoint file with the SMART. We are certain that the SMART is a simple and practical solution for measuring RTs accurately. Although there are some restrictions in using the SMART with RT paradigms, the SMART is capable of providing both researchers and health professionals working in clinical settings with new ways of using RT paradigms in their work.

Effects of prenatal exposure to polychlorinated biphenyls and dioxins on mental and motor development in Japanese children at 6 months of age.

Several studies have shown that prenatal and/or postnatal background-level exposure to environmental chemicals, such as polychlorinated biphenyls (PCBs) and dioxins, induces adverse effects on the neurodevelopment of children. However, other studies have not detected any harmful influences on neurodevelopment. Furthermore, except in western countries, no developmental tests have been carried out in relation to detailed assessment of exposure to PCBs and dioxins. In this study (the Hokkaido Study on Environment and Children's Health), the effect of prenatal exposure to background levels of PCBs and dioxins on infant neurodevelopment in Japan/Sapporo was elucidated. The associations between the total or individual isomer level of PCBs and dioxins in 134 Japanese pregnant women's peripheral blood and the mental or motor development of their 6-month-old infants were evaluated using the second edition of the Bayley Scales of Infant Development. The mean level of total toxicity equivalency quantity (TEQ) was 18.8 (4.0-51.2) pg/g lipid in blood of 134 mothers. After adjustment for potential confounding variables, the total TEQ value was shown not to be significantly associated with mental developmental index (MDI) or psychomotor developmental index (PDI). However, the levels of one polychlorinated dibenzo-p-dioxin (PCDD) isomer, total PCDDs, and total PCDDs/polychlorinated dibenzofurans (PCDFs) were significantly negatively associated with MDI, and the levels of two PCDD isomers and three PCDF isomers were significantly negatively associated with the PDI. In conclusion, the background-level exposure of several isomers of dioxins during the prenatal period probably affects the motor development of 6-month-old infants more than it does their mental development.

[Non-radioactive PCR southern method for analysis of CTG repeat in myotonic dystrophy].

Myotonic dystrophy (MyD) is a hereditary neuromuscular disorder of an autosomal dominant trait. MyD is caused by an expansion of unstable CTG trinucleotide repeat in the 3' untranslated region of mRNA coding myotonin protein kinase (MT-PK). We analyzed CTG repeat expansion in 10 patients with congenital MyD and their relatives using the non-radioactive PCR Southern method. The region containing the CTG repeat was amplified by PCR using specific primers. The PCR products were electrophoresed on a 1% agarose gel and transferred to a nylon membrane. The CTG repeat expansion was shown using a fluorescein-labelled (CTG) 10 probe. To estimate the number of CTG repeats, we compared the smears obtained on Southern blotting with a picture of PCR products and a DNA size marker (100 bp). We compared our results of radioactive Southern blotting for genomic DNA digested by Eco RI or Bgl I and for PCR products. In congenital MyD patients, heterogeneous smears (3.89-10.22 kb:about 1252-3362 CTG repeat) were observed, whereas in the adult type MyD had heterogeneous smears (0.92-1.82 kb:about 262-562 CTG repeat). In asymptomatic MyD patients, there were heterogeneous smears (0.35-1.16 kb:about 72-342 CTG repeat). These results demonstrated anticipation. We conclude that the non-radioactive PCR Southern method is useful and convenient for the DNA diagnosis of MyD.